OPERATING DEVICE FOR A LAMP HAVING A POWER CORRECTION CIRCUIT

• US 20140125247A1
• Filed: 04/26/2012
• Published: 05/08/2014
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: Tridonic GmbH & Co. KG (Zumtobel Group AG)
• Original Assignee: Tridonic GmbH & Co. KG (Zumtobel Group AG)
• Inventors: Mitterbacher, Andre
• Granted Patent: US 8,994,286 B2
• Time in Patent Office: Days
• US Class Current: 315/224
• CPC Class Codes: H02M 1/42 Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 47/14 by determining electrical parameters of the light source
• CPC Class Codes: H05B 47/17 Operational modes, e.g. switching from manual to automatic mode or prohibiting specific operations
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

For the purpose of power factor correction of an operating device for a lamp, an inductor (7) is supplied with an input voltage (Vin), a controllable switch element (13) coupled with the inductor (7) being opened or closed to optionally charge or discharge the inductor (7). A control unit (14) for controlling the switch element (13) is designed such that it determines, depending on an output voltage (Vout) of the power factor correction circuit, a switch-on time (Ton) for switching the switch element (13) on and controls the switch element (13) optionally according to at least a first operating mode and a second operating mode, the operation in the first operating mode and the operation in the second operating mode being dependent on the duration of the determined switch-on time (Ton).

Claims

1. An operating device (3) for a lamp having a power factor correction circuit (2), the operating device comprising

an input terminal (4) for receiving an input voltage (Vin),

an inductance (7), which is coupled to the input terminal (4),

a controllable switch (13), which is coupled to the inductance (7), and which charges or discharges the inductance (7) by closing or opening,

an output terminal (5) for outputting an output voltage (Vout), and

a control unit (14) for actuating the switch (13), wherein the control unit (14) is configured such that the control unit (14) determines a switch-on time (Ton) for switching on the switch (13) depending on the output voltage (Vout) and actuates the switch (13) in accordance with either at least a first operating mode or a second operating mode,

the control unit (14) is configured such that the control unit (14) actuates the switch (13) depending on the duration of the determined switch-on time (Ton) in accordance with either the first operating mode or the second operating mode.

2. The operating device (3) for a lamp as claimed in claim 1, wherein the control unit (14) is configured in such a way that the control unit (14) determines the switch-on time (Ton) for the switch (13) based on a comparison of a setpoint switch-on time determined depending on the output voltage and a minimum switch-on time (Ton_min).

3. The operating device (3) for a lamp as claimed in claim 2, wherein the minimum switch-on time (Ton_min) is variable for matching a transition between the first operating mode and the second operating mode.

4. The operating device (3) for a lamp as claimed in claim 2, wherein the control unit (14) is configured such that the control unit (14) actuates the switch (13) in accordance with the first operating mode if the setpoint switch-on time is greater than the minimum switch-on time (Ton_min), while the control unit (14) actuates the switch (13) in accordance with the second operating mode.

5. The operating device (3) for a lamp as claimed in claim 2, wherein the control unit (14) is configured such that, in the first operating mode, it switches on the switch (13) for the duration of the setpoint switch-on time, then switches off the switch (13) and only switches on the switch (13) again when, during discharge of the inductance (7), a current (I_L) through the inductance (7) has decreased to a specific current limit value.

6. The operating device (3) for a lamp as claimed in claim 2, wherein the control unit (14) is configured such that, in the second operating mode, the control unit switches on the switch (13) for the duration of the minimum switch-on time (Ton_min), then switches off the switch (13) and only switches on the switch (13) again once a wait time (Twait) has elapsed when it is established that a current (I_L) through the inductance (7) has decreased to a specific current limit value during discharge of the inductance (7).

7. The operating device (3) for a lamp as claimed in claim 6, wherein the control unit (14) is configured such that the control unit (14) determines a difference between the setpoint switch-on time and the minimum switch-on time (Ton_min) and establishes the wait time (Twait) depending on the difference.

8. The operating device (3) for a lamp as claimed in claim 6, wherein the control unit (14) establishes the wait time (Twait) depending on the difference on the basis of a predetermined characteristic.

9. The operating device (3) for a lamp as claimed in claim 5, wherein the current limit value is zero.

10. The operating device (3) for a lamp as claimed in claim 1, wherein the controllable switch (13) is coupled to the output terminal (5) via a diode (8), with the result that, during discharge of the inductance (7), a current (I_L) through the inductance (7) is supplied to the output terminal (5) via the diode (8).

11. The operating device (3) for a lamp as claimed in claim 10, wherein the first operating mode is an operating mode with a current (I_L) through the inductance (7) in the limit range between a continuous and a discontinuous current.

12. The operating device (3) for a lamp as claimed in claim 10, wherein the second operating mode is an operating mode with a discontinuous current (IL) through the inductance (7).

13. The operating device (3) for a lamp as claimed in claim 10, wherein a detector (10-12), which is coupled to the control unit (14), which detects a measured variable corresponding to the output voltage (Vout) and a measured variable corresponding to a zero crossing of the current (IL) through the inductance (7) are provided.

15. A method for operating an operating device (3) for a lamp having power factor correction for an AC-to-DC converter (1, 2), the method comprising:

applying an input voltage (Vin) to an inductance (7),

charging and discharging the inductance (7) by closing and opening a switch (13) coupled to the inductance (7),

establishing a switch-on time (Ton) for the switch (13) depending on an output voltage (Vout) of the converter (1, 2), and

actuating the switch (13) in accordance with either at least a first operating mode or a second operating mode,

wherein the switch (13) is actuated either in accordance with the first operating mode or the second operating mode depending on the duration of the established switch-on time (Ton), wherein the method is implemented using an operating device (3) for a lamp as claimed in claim 1.

14. A method for operating an operating device (3) for a lamp having power factor correction for an AC-to-DC converter (1, 2), the method comprising:

applying an input voltage (Vin) to an inductance (7),

charging and discharging the inductance (7) by closing and opening a switch (13) coupled to the inductance (7),

establishing a switch-on time (Ton) for the switch (13) depending on an output voltage (Vout) of the converter (1, 2), and

actuating the switch (13) in accordance with either at least a first operating mode or a second operating mode,

wherein the switch (13) is actuated either in accordance with the first operating mode or the second operating mode depending on the duration of the established switch-on time (Ton).